Consumption rate of phytonematodes by Pergalumna sp. (Acari: Oribatida: Galumnidae) under laboratory conditions determined by a new method

Abstract

Although several generalist species of Pergalumna are known to be nematode predators, the potential of oribatid mites as natural enemies of phytonematodes has been underestimated. The objective of this work was to estimate the consumption rate of a Pergalumna sp. when feeding on two major pest nematodes, Meloidogyne javanica and Pratylenchus coffeae, under laboratory conditions. A new method was used, in which live nematodes are offered to mites and subsequently consumption is quantified based on the sclerotized, well preserved structures in the mite's fecal pellets. The assay was evaluated during 5 days, at 25 degrees C and 96% relative humidity, with three replicates for each nematode species. Every replicate consisted of a group of four mites isolated in an arena, to which 400 nematodes were transferred daily. The daily produced fecal pellets were mounted in Hoyer's medium for examination under a microscope. The nematode buccal stylets and cephalic frameworks were counted to estimate the number of nematodes consumed. It was estimated that a single mite daily ingested 18.3 +/- 0.8 (mean +/- SE) M. javanica (J(2) juveniles) or 41.6 +/- 7.2 P. coffeae (juveniles + adults), the maximal daily consumption being 34 M. javanica and 73 P. coffeae. The method showed to be practical, precise and suitable for laboratory studies in which nematophagous mites classified as engulfers are included.

Free‐living nematodes as prey for higher trophic levels of forest soil food webs

“…The results support earlier findings based on parasitic nematodes used as model nematode prey (Heidemann et al ) and suggests that S. magnus indeed feeds on free‐living soil nematodes. Each of the oribatid mite species studied, including Galumna spp., preferentially fed on small nematodes confirming earlier suggestions that if feeding on nematodes oribatid mites prefer to feed on small nematode species (Rockett and Woodring , Muraoka and Ishibashi , Rockett , Oliveira et al ). Low frequency of prey detection in P. peltifer, A. coleoptrata and Carabodes spp.…”

Predation of entomopathogenic nematodes by Sancassania sp. (Acari: Acaridae)

“…may be able to capture the larger S. feltiae easier than the smaller H. bacteriophora. Our Wndings are in agreement with Oliveira et al (2007) who found that the oribatid mite, Pergalumna sp., consumed more of the larger adult Pratylenchus coVeae (550-680 m) than the smaller second-stage juvenile Meloidogyne javanica (380 m). Finally, steinernematid IJs are known to exsheath the second-stage cuticle readily whereas heterorhabditid species tend to retain the second-stage cuticle (Timper and Kaya 1989).…”

“…In addition, our data showed that a female adult mite can attack, on average, 40 IJs over a 24-h period. This average "attack" rate is similar to that observed by Oliveira et al (2007) who documented an average daily consumption of 42 Pratylenchus coVeae, a plant-parasitic nematode (PPN), by the mite, Pergalumna sp. (Acari: Oribatidae).…”

The Mesostigmatid Mite Protogamasellus mica, an Effective Predator of Free-Living and Plant-Parasitic Nematodes

“…This is similar to the levels of consumption and/or damage observed in laboratory studies with other mites. For example, Oliveira et al (2007) estimated that a single oribatid mite (Pergalumna sp.) consumed 18 juveniles of M. javanica and 42 adults and juveniles of Pratylenchus coffeae per day whereas a species of Sancassania killed about 40 entomopathogenic nematodes in a day (Karagoz et al, 2007).…”